Analysis The Effects Of Three Boundary Layer Parameterization Schemes On The Numerical Simulation Results Of Severe Convection Weather

Based on the conventional observation data,satellite products,doppler radar data and precipitation fusion products,using the mesoscale numerical model(WRF v3.4)of coupled MRF,UW and YSU boundary layer scheme analyze and simulate the severe convection weather process in Zhejiang regions of single underlying surface and Gansu regions of complex underlying surface respectively.Through numerical experiments and comparative analysis,the effects of three boundary layer schemes on the triggering mechanism of two convective precipitation,the macroscopic and microscopic evolution characteristics of the convective system and the simulation results of precipitation mechanism were studied.The results showed that:Under the conditions of different boundary layer parameterization schemes,the model simulate different cloud macroscopic and microscopic characteristics.In the case of Zhejiang province,radar reflectance evolution characteristics simulated by of YSU and MRF schemes are in good agreement with the real situation.The air is well configured in high and low altitude,and the water vapor transportation is abundant,making the precipitation intensity strong.In terms of microphysical structure,under strong updraft,lots of cloud water becomes subcooled cloud water,graupel is frozen against plenty of subcooled cloud water resulting in high specific water content of graupel particles,and the process of graupel melting to generate rain water is relatively strong.The simulated radar echo of UW scheme deviates greatly from the real situation because the macroscopic triggering condition of the simulated convection is poor.The cloud water content above the zero layer is relatively low,which means growth of graupel particles is limited and less rain water generated by graupel particle melting.In the case of gansu,three boundary layer parameterization schemes can simulate the development,maturity and dissipation stages of convective clouds,and the macroscopic conditions conducive to the occurrence and development of convection simulated by MRF and UW schemes are better and precipitation intensity is strong.The specific moisture content of hydrometeors in the cloud is relatively high,and the process of graupel and snow melting to generate rain water is relatively strong,which makes the precipitation intensity strong.However,the dynamic lifting conditions and water vapor conditions simulated by YSU scheme are relatively poor,and the specific moisture content of various hydromorphous particles is relatively small,and the degree of mutual transformation is low,resulting in weak precipitation intensity.In conclusion,the boundary layer parameterization scheme may have different simulation effects on severe convective precipitation in different regions.Among the three schemes,the two regional convective precipitation intensity simulated by MRF scheme are all strong,and the treat score of accumulation precipitation simulated by UW scheme is all high,but the precipitation characteristics simulated by YSU scheme are quite different in different regions.